U.S. patent number 6,750,183 [Application Number 09/746,044] was granted by the patent office on 2004-06-15 for lubricating oil composition.
This patent grant is currently assigned to Infineum International Ltd.. Invention is credited to Ricardo A. Bloch, Nancy Z. Diggs, Jacob Emert, Fredrick W. Girschick, Antonio Gutierrez, David J. Martella, Mark G. Stevens.
United States Patent |
6,750,183 |
Gutierrez , et al. |
June 15, 2004 |
**Please see images for:
( Certificate of Correction ) ** |
Lubricating oil composition
Abstract
Lubricating oil compositions providing superior soot dispersing
characteristics, which contain a combination of a high molecular
weight dispersant and a soot dispersant comprising a linked
aromatic oligomer.
Inventors: |
Gutierrez; Antonio
(Mercerville, NJ), Bloch; Ricardo A. (Scotch Plains, NJ),
Diggs; Nancy Z. (Westfield, NJ), Girschick; Fredrick W.
(Scotch Plains, NJ), Martella; David J. (Princeton, NJ),
Stevens; Mark G. (Metuchen, NJ), Emert; Jacob (Brooklyn,
NY) |
Assignee: |
Infineum International Ltd.
(GB)
|
Family
ID: |
24999265 |
Appl.
No.: |
09/746,044 |
Filed: |
December 22, 2000 |
Current U.S.
Class: |
508/329; 508/332;
508/387; 508/452; 508/457; 508/463; 508/465; 508/518; 508/543;
508/552; 508/565; 508/575; 508/578; 508/580; 508/585; 528/271;
528/310; 528/367; 528/373 |
Current CPC
Class: |
C07C
45/46 (20130101); C07C 49/788 (20130101); C07D
215/14 (20130101); C10M 141/06 (20130101); C10M
161/00 (20130101); C07C 45/46 (20130101); C07C
49/788 (20130101) |
Current International
Class: |
C07C
49/788 (20060101); C07D 215/00 (20060101); C07C
45/00 (20060101); C07C 49/00 (20060101); C07D
215/14 (20060101); C07C 45/46 (20060101); C10M
141/06 (20060101); C10M 141/00 (20060101); C10M
161/00 (20060101); C10M 129/00 (); C10M 145/00 ();
C10M 133/00 (); C10M 151/00 (); C10M 135/00 () |
Field of
Search: |
;508/578,580,585,552,465,463,518,543,457,452,329,332,565
;528/271,310,367,373 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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WO87/04180 |
|
Jul 1987 |
|
WO |
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WO89/00186 |
|
Jan 1989 |
|
WO |
|
Other References
"Chemical Modifications of Furan-Based Calixarenes by Diels-Alder
Reaction", Cafeo, Grazia et al. Chemistry--A European Journal
(1999), 5(1), 356-358, vol. 5, No. 1, XP002209075..
|
Primary Examiner: Howard; Jacqueline V.
Claims
What is claimed is:
1. A lubricating oil composition comprising a major amount of an
oil of lubricating viscosity; a minor amount of a high molecular
weight, nitrogen-containing dispersant; and a minor amount of an
oligomer of the formula: ##STR7##
wherein each Ar independently represents an aromatic moiety
selected from polynuclear carbocyclic moieties, said aromatic
moiety being optionally substituted by 1 to 6 substituents selected
from H, --OR.sub.1, --N(R.sub.1).sub.2, F, Cl, Br, I, -(L-(Ar)-T),
--S(O).sub.w R.sub.1, -(CZ).sub.y -(Z).sub.y --R, and -(Z).sub.y
-(CZ).sub.x --R.sub.1, wherein w is 0 to 3, each Z is independently
O, --N(R.sub.1).sub.2 or S, x and y are independently 0 or 1 and
each R.sub.1 is independently H or a linear or branched, saturated
or unsaturated hydrocarbyl group having from 1 to about 200 carbon
atoms, optionally mono- or poly-substituted with one or more groups
selected from --OR.sub.2, --N(R.sub.2).sub.2, F, Cl, Br, I,
--S(O).sub.w R.sub.2, -(CZ).sub.x -(Z).sub.y --R.sub.2 and
-(Z).sub.y -(CZ).sub.x --R.sub.2, wherein w, x, y and Z are as
defined above and R.sub.2 is a hydrocarbyl group having 1 to about
200 carbon atoms; each L is independently a linking moiety
comprising a carbon--carbon single bond or a linking group; each T
is independently H, OR.sub.1, N(R.sub.1).sub.2, F, Cl, Br, I,
S(O).sub.w R.sub.1, (CZ).sub.x -(Z).sub.y --R.sub.1 or (Z).sub.y
-(CZ).sub.x --R.sub.1, wherein R.sub.1, w, x, y and Z are as
defined above; and n is 2 to about 1000; wherein at least 25% of
aromatic moieties (Ar) are connected to at least 2 linking moieties
(L) and a ratio of the total number of aliphatic carbon atoms in
the oligomer to the total number of aromatic ring atoms in aromatic
moieties (Ar) is from about 0.10:1 to about 40:1.
2. The lubricating oil composition of claim 1, wherein said ratio
of the total number of aliphatic carbon atoms in the oligomer to
the total number of aromatic ring atoms in aromatic moieties (Ar)
is from about 4:1 to about 7:1.
3. The lubricating oil composition of claim 1, wherein at least 60%
of aromatic moieties (Ar) are substituted.
4. The lubricating oil composition of claim 1, wherein hydrocarbyl
groups R.sub.1 and R.sub.2 have from 1 to about 30 carbon
atoms.
5. The lubricating oil composition of claim 1, wherein each of said
linking moieties (L) is independently selected from an alkylene
linkage, an ether linkage, an ester linkage, an anhydride linkage,
an ether-acyl linkage, an ether ester linkage, an acyl-ester
linkage, an amino linkage, an amido linkage, a carbamido linkage, a
urethane linkage and a sulfur linkage, each of the linkage groups
being optionally mono- or polysubstituted with OR.sub.1,
N(R.sub.1).sub.2, F, Cl, Br, I, S(O).sub.w R.sub.1, (CZ).sub.x
-(Z).sub.y --R.sub.1 or (Z).sub.y -(CZ).sub.x --R.sub.1, wherein w,
Z and R.sub.1 are as defined in claim 1.
6. The lubricating oil composition of claim 5, wherein said linkage
moieties are selected from alkylene linkages --CH.sub.3
CHC(CH.sub.3).sub.2 - and --C(CH.sub.3).sub.2 -, diacyl
linkages--COCO--and --CO(CH.sub.2).sub.4 CO--, and sulfur linkages
--S.sub.1- and --S.sub.2 --.
7. The lubricating oil composition of claim 1, wherein aromatic
moiety (Ar) is selected from naphthalene and quinoline.
8. The lubricating oil composition of claim 1, wherein said high
molecular weight dispersant is present in an amount providing from
about 0.008 to about 0.32 wt. % of nitrogen, and said oligomer is
present in an amount of from about 0.005 to about 10 wt. %, based
on the total weight of lubricating oil composition.
9. An oligomer of the formula: ##STR8##
wherein each Ar independently represents an aromatic moiety
selected from polynuclear carbocyclic moieties, said aromatic
moiety being optionally substituted by 1 to 6 substituents selected
from H, --OR.sub.4, --N(R.sub.4).sub.2, F, Cl, Br, I, --(L-(Ar)-T),
--S(O).sub.w R.sub.4, -(CZ).sub.x -(Z).sub.y --R.sub.4 and
-(Z).sub.y -(CZ).sub.x --R.sub.4, wherein w is 0 to 3, each Z is
independently O, --N(R.sub.4).sub.2 or S, x and y are independently
0 or 1 and each R.sub.4 is independently H, methyl, ethyl, propyl
or a branched hydrocarbyl group having 3 to 200 carbon atoms,
optionally mono- or poly-substituted with one or more groups
selected from --OR.sub.4, --N(R.sub.4).sub.2, F, Cl, Br, I,
--S(O).sub.w R.sub.4, --(CZ).sub.x --(Z).sub.y --R.sub.4 and
-(Z).sub.y -(CZ).sub.x R.sub.4, wherein w, x, y R4 and Z are as
defined above; each L is independently a linking moiety comprising
a carbon--carbon single bond or a linking group; each T is
independently H, OR.sub.1, N(R.sub.4).sub.2, F, Cl, Br, I,
S(O).sub.w R.sub.4, (CZ).sub.x --(Z).sub.y --R.sub.4 or (Z).sub.y
-(CZ).sub.x --R.sub.4, wherein R.sub.4, w, x, y and Z are as
defined above; and n is 2 to about 1000; wherein at least 25% of
aromatic moieties (Ar) are connected to at least 2 linking moieties
(L) and a ratio of the total number of aliphatic carbon atoms in
the oligomer to the total number of aromatic ring atoms in aromatic
moieties (Ar) is from about 0.10:1 to about 40:1.
10. The oligomer of claim 9, wherein said ratio of the total number
of aliphatic carbon atoms in the oligomer to the total number of
aromatic ring atoms in aromatic moieties (Ar) is from about 4:1 to
about 7:1.
11. The oligomer of claim 9, wherein at least 60% of aromatic
moieties (Ar) are substituted.
12. The oligomer of claim 9, wherein hydrocarbyl groups R.sub.4 and
R.sub.5 have from 1 to about 30 carbon atoms.
13. The oligomer of claim 9, wherein each of said linking moieties
(L) is independently selected from an alkylene linkage, an ether
linkage, an ester linkage, an anhydride linkage, an ether-acyl
linkage, an ether ester linkage, an acyl-ester linkage, an amino
linkage, an amido linkage, a carbamido linkage, a urethane linkage
and a sulfur linkage, each of the linkage groups being optionally
mono- or polysubstituted with OR.sub.1, N(R.sub.1).sub.2, F, Cl,
Br, I, S(O).sub.w R.sub.l, (CZ).sub.x -(Z).sub.y --R.sub.1 or
(Z).sub.y -(CZ).sub.x --R.sub.1, wherein w, Z and R.sub.1 are as
defined in claim 1.
14. The oligomer of claim 13, wherein said linkage moieties are
selected from alkylene linkages --CH.sub.3 CHC(CH.sub.3).sub.2 --
and --C(CH.sub.3).sub.2 --, diacyl linkages--COCO-- and
--CO(CH.sub.2).sub.4 CO--, and sulfur linkages --S.sub.1- and
--S.sub.2 --.
15. The oligomer of claim 9, wherein aromatic moiety (Ar) is
selected from naphthalene and quinoline.
Description
FIELD OF THE INVENTION
This invention relates to crankcase lubricating oil compositions.
More specifically, the invention is directed to lubricating oil
compositions that exhibit soot dispersing characteristics
sufficient to allow the lubricating oil composition to pass an
industry standard T8 test, with reduced levels of additive
nitrogen.
BACKGROUND OF THE INVENTION
Lubricating oil compositions comprise a major amount of a base oil
and additives that improve the performance and increase the useful
life of the lubricant. Nitrogen-containing dispersants are commonly
used lubricant additives. The function of a dispersant is to
maintain in suspension within the oil, insoluble materials formed
by oxidation and other mechanisms during use of the oil, to prevent
sludge flocculation and precipitation of the insoluble materials.
Another function of the dispersant is to reduce the agglomeration
of soot particles, thus reducing increases in the viscosity of the
lubricating oil upon use. Crankcase lubricants providing improved
performance, including improved soot dispersancy, have been
continuously demanded.
To improve soot dispersancy, the industry has moved to the use
higher molecular weight materials, which have superior dispersancy
properties compared to lower molecular weight materials, and to use
the high molecular weight dispersants in ever increasing amounts.
However, dispersants are expensive. Further, common methods for
forming high molecular weight, nitrogen-containing dispersants
leave residual chlorine, which is introduced into the lubricant
with the dispersant. The presence of chlorine leads to problems
with the disposal of used lubricants, and lubricants containing
reduced amounts of chlorine have been demanded. Also, greater
levels of high molecular weight dispersant do not blend well in
lubricants also containing overbased detergents. Still further, a
high level of basic amine from dispersants contributes to the
deterioration of seals within the engine during service. Therefore,
it would be advantageous to provide a lubricant with adequate soot
dispersancy properties using reduced amounts of high molecular
weight, nitrogen-containing dispersant.
U.S. Pat. No. 1,815,022 to Davis (1931) discloses condensates of
naphthalene and essentially linear chlorinated waxes formed by
Freidel Craft alkylation of the naphthalene. Such compounds were
described as functioning as wax crystal modifiers or lube oil flow
improver (LOFI) additives and were added to oil to improve the cold
flow characteristics thereof. These compounds have not been used
for a number of years and, due to a high chlorine content, these
compounds would be considered unsuitable for use in a modern
passenger car, or heavy duty diesel motor oil formulations. In
modern formulations, these compounds have been supplanted by
fumarate/vinyl acetate copolymers or polymethacrylate-based
LOFIs.
U.S. Pat. No. 4,708,809 to Davis describes a lubricating oil
composition containing a phenolic compound of the formula:
wherein R is a saturated hydrocarbon group having 10 or more
aliphatic carbon atoms; a and b are each independently 1 to 3 times
the number of aromatic nuclei present in Ar; and Ar is a single,
fused or linked polynuclear ring moiety that is optionally
substituted. It is alleged that the addition of a minor amount of
such a compound to a lubricant composition that is mixed with fuel
will lead to a reduction in piston ring sticking in a two cycle
engine.
SUMMARY OF THE INVENTION
The present invention, in brief summary, is directed to crankcase
lubricating oils comprising a major amount by weight of an oil of
lubricating viscosity; a minor amount by weight of a high molecular
weight, nitrogen-containing dispersant; and an amount of an oil
soluble, or oil dispersible aromatic hydrocarbyl oligomer
sufficient to provide the lubricating composition with improved
soot dispersing properties.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 compares graphically the soot induced viscosity increase, as
measured using a Haake carbon black test, in a formulated
lubricating oil containing a high molecular weight dispersant; a
formulated lubricating oil containing a combination of a high
molecular weight dispersant and 1 wt. % of an alkylated, linked
aromatic oligomer of the present invention; and a formulated
lubricating oil containing a combination of a high molecular weight
dispersant and 1 wt. % of a comparative, unlinked alkylated
aromatic compound.
FIG. 2 compares graphically the soot induced viscosity increase, as
measured using a Haake carbon black test, in a formulated
lubricating oil containing a high molecular weight dispersant; a
formulated lubricating oil containing a combination of a high
molecular weight dispersant and 2 wt. % of an alkylated, linked
aromatic oligomer of the present invention; and a formulated
lubricating oil containing a combination of a high molecular weight
dispersant and 2 wt. % of a comparative, unlinked alkylated
aromatic compound.
DETAILED DESCRIPTION OF THE INVENTION
The lubricating oil compositions of the present invention comprise
a major amount of an oil of lubricating viscosity. Oils of
lubricating viscosity useful in the context of the present
invention may be selected from natural lubricating oils, synthetic
lubricating oils and mixtures thereof. The lubricating oil may
range in viscosity from light distillate mineral oils to heavy
lubricating oils such as gasoline engine oils, mineral lubricating
oils and heavy duty diesel oils. Generally, the viscosity of the
oil ranges from about 2 centistokes to about 40 centistokes,
especially from about 4 centistokes to about 20 centistokes, as
measured at 100.degree.0 C.
Natural oils include animal oils and vegetable oils (e.g., castor
oil, lard oil); liquid petroleum oils and hydrorefined,
solvent-treated or acid-treated mineral oils of the paraffinic,
naphthenic and mixed paraffinic-naphthenic types. Oils of
lubricating viscosity derived from coal or shale also serve as
useful base oils.
Synthetic lubricating oils include hydrocarbon oils and
halo-substituted hydrocarbon oils such as polymerized and
interpolymerized olefins (e.g., polybutylenes, polypropylenes,
propylene-isobutylene copolymers, chlorinated polybutylenes,
poly(1-hexenes), poly(1-octenes), poly(1-decenes)); alkylbenzenes
(e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes,
di(2-ethylhexyl)benzenes); polyphenyls (e.g., biphenyls,
terphenyls, alkylated polyphenols); and alkylated diphenyl ethers
and alkylated diphenyl sulfides and derivative, analogs and
homologs thereof.
Alkylene oxide polymers and interpolymers and derivatives thereof
where the terminal hydroxyl groups have been modified by
esterification, etherification, etc., constitute another class of
known synthetic lubricating oils. These are exemplified by
polyoxyalkylene polymers prepared by polymerization of ethylene
oxide or propylene oxide, and the alkyl and aryl ethers of
polyoxyalkylene polymers (e.g., methyl-polyiso-propylene glycol
ether having a molecular weight of 1000 or diphenyl ether of
poly-ethylene glycol having a molecular weight of 1000 to 1500);
and mono- and polycarboxylic esters thereof, for example, the
acetic acid esters, mixed C.sub.3 -C.sub.8 fatty acid esters and
C.sub.13 oxo acid diester of tetraethylene glycol.
Another suitable class of synthetic lubricating oils comprises the
esters of dicarboxylic acids (e.g., phthalic acid, succinic acid,
alkyl succinic acids and alkenyl succinic acids, maleic acid,
azelaic acid, suberic acid, sebasic acid, fumaric acid, adipic
acid, linoleic acid dimer, malonic acid, alkylmalonic acids,
alkenyl malonic acids) with a variety of alcohols (e.g., butyl
alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol,
ethylene glycol, diethylene glycol monoether, propylene glycol).
Specific examples of such esters includes dibutyl adipate,
di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate,
diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl
phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic
acid dimer, and the complex ester formed by reacting one mole of
sebacic acid with two moles of tetraethylene glycol and two moles
of 2-ethylhexanoic acid.
Esters useful as synthetic oils also include those made from
C.sub.5 to C.sub.12 monocarboxylic acids and polyols and polyol
esters such as neopentyl glycol, trimethylolpropane,
pentaerythritol, dipentaerythritol and tripentaerythritol.
Silicon-based oils such as the polyalkyl-, polyaryl-, polyalkoxy-
or polyaryloxysilicone oils and silicate oils comprise another
useful class of synthetic lubricants; such oils include tetraethyl
silicate, tetraisopropyl silicate, tetra-(2-ethylhexyl)silicate,
tetra-(4-methyl-2-ethylhexyl)silicate, tetra-(p-tert-butyl-phenyl)
silicate, hexa-(4-methyl-2-ethylhexyl)disiloxane,
poly(methyl)siloxanes and poly(methylphenyl)siloxanes. Other
synthetic lubricating oils include liquid esters of
phosphorous-containing acids (e.g., tricresyl phosphate, trioctyl
phosphate, diethyl ester of decylphosphonic acid) and polymeric
tetrahydrofurans.
Unrefined, refined and re-refined oils can be used in lubricants of
the present invention. Unrefined oils are those obtained directly
from a natural or synthetic source without further purification
treatment. For example, a shale oil obtained directly from
retorting operations; petroleum oil obtained directly from
distillation; or ester oil obtained directly from an esterification
and used without further treatment would be an unrefined oil.
Refined oils are similar to unrefined oils except that the oil is
further treated in one or more purification steps to improve one or
more properties. Many such purification techniques, such as
distillation, solvent extraction, acid or base extraction,
filtration and percolation are known to those skilled in the art.
Re-refined oils are obtained by processes similar to those used to
provide refined oils but begin with oil that has already been used
in service. Such re-refined oils are also known as reclaimed or
reprocessed oils and are often subjected to additional processing
using techniques for removing spent additives and oil breakdown
products.
HIGH MOLECULAR WEIGHT DISPERSANT
The high molecular weight dispersants useful in the context of the
present invention include the range of higher molecular weight
ashless (metal-free) dispersants known to be effective to reduce
formation of deposits upon use in gasoline and diesel engines, when
added to lubricating oils. The ashless, high molecular weight
dispersant useful in the compositions of the present invention
comprises an oil soluble polymeric long chain backbone having
functional groups capable of associating with particles to be
dispersed. Typically, such dispersants comprise amine, alcohol,
amide or ester polar moieties attached to the polymer backbone,
often via a bridging group. The ashless, high molecular weight
dispersant may be, for example, selected from oil soluble salts,
esters, amino-esters, amides, imides and oxazolines of long chain
hydrocarbon-substituted mono- and polycarboxylic acids or
anhydrides thereof; thiocarboxylate derivatives of long chain
hydrocarbons; long chain aliphatic hydrocarbons having polyamine
moieties attached directly thereto; and Mannich condensation
products formed by condensing a long chain substituted phenol with
formaldehyde and polyalkylene polyamine.
A "high molecular weight" dispersant is one having a number average
molecular weight greater than or equal to 4,000, such as between
4,000 and 20,000. The precise molecular weight ranges will depend
on the type of polymer used to form the dispersant, the number of
functional groups present, and the type of polar functional group
employed. For example, for a polyisobutylene derivatized
dispersant, a high molecular weight dispersant is one formed with a
polymer backbone having a number average molecular weight of from
about 1700 to about 5600. Typical commercially available
polyisobutylene-based dispersants contain polyisobutylene polymers
having a number average molecular weight ranging from about 900 to
about 2300, functionalized by maleic anhydride (MW=98), and
derivatized with polyamines having a molecular weight of from about
100 to about 350. Polymers of lower molecular weight may also be
used to form high molecular weight dispersants by incorporating
multiple polymer chains into the dispersant, which can be
accomplished using methods known in the art.
Polymer molecular weight, specifically Mn, can be determined by
various known techniques. One convenient method is gel permeation
chromatography (GPC), which additionally provides molecular weight
distribution information (see W. W. Yau, J. J. Kirkland and D. D.
Bly, "Modem Size Exclusion Liquid Chromatography", John Wiley and
Sons, New York, 1979). If the molecular weight of an
amine-containing dispersant (e.g., PIBSApolyamine or PIBSA-PAM) is
being determined, the presence of the amine may cause the
dispersant to be adsorbed by the column, leading to an inaccurate
molecular weight determination. Persons familiar with the operation
of GPC equipment understand that this problem may be eliminated by
using a mixed solvent system, such as tetrahydrofuran (THF) mixed
with a minor amount of pyridine, as opposed to pure THF. The
problem may also be addressed by capping the amine with acetic
anhydride and correcting the molecular weight based on the number
of capping groups. Another useful method for determining molecular
weight, particularly for lower molecular weight polymers, is vapor
pressure osmometry (see, e.g., ASTM D3592).
The degree of polymerisation DP of a polymer is: ##EQU1##
and thus for the copolymers of two monomers D.sub.P may be
calculated as follows: ##EQU2##
Preferably, the degree of polymerisation for the polymer backbones
used in the invention is at least 30, typically from 30 to 165,
more preferably 35 to 100.
The preferred hydrocarbons or polymers employed in this invention
include homopolymers, interpolymers or lower molecular weight
hydrocarbons. One family of useful polymers comprise polymers of
ethylene and/or at least one C.sub.3 to C.sub.28 alpha-olefin
having the formula H.sub.2 C.dbd.CHR.sup.1, wherein R.sup.1 is
straight or branched chain alkyl radical comprising 1 to 26 carbon
atoms and wherein the polymer contains carbon-to-carbon
unsaturation, preferably a high degree of terminal ethenylidene
unsaturation. One preferred class of such polymers employed in this
invention comprise interpolymers of ethylene and at least one
alpha-olefin of the above formula, wherein R.sup.1 is alkyl of from
1 to 18 carbon atoms, and more preferably is alkyl of from 1 to 8
carbon atoms, and more preferably still of from 1 to 2 carbon
atoms. Therefore, useful alpha-olefin monomers and comonomers
include, for example, propylene, butene-1, hexene-1,
octene-1,4-methylpentene-1, decene-1, dodecene-1, tridecene-1,
tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1,
octadecene-1, nonadecene-1, and mixtures thereof (e.g., mixtures of
propylene and butene-1, and the like). Exemplary of such polymers
are propylene homopolymers, butene-1 homopolymers, propylene-butene
copolymers, ethylene-propylene copolymers, ethylene-butene-1
copolymers and the like, wherein the polymer contains at least some
terminal and/or internal unsaturation. Preferred polymers are
unsaturated copolymers of ethylene and propylene and ethylene and
butene-1. The interpolymers of this invention may contain a minor
amount, e.g. 0.5 to 5 mole % of a C.sub.4 to C.sub.18
non-conjugated diolefin comonomer. However, it is preferred that
the polymers of this invention comprise only alpha-olefin
homopolymers, interpolymers of alpha-olefin comonomers and
interpolymers of ethylene and alpha-olefin comonomers. The molar
ethylene content of the polymers employed in this invention is
preferably in the range of 20 to 80%, and more preferably 30 to
70%. When propylene and/or butene-1 are employed as comonomer(s)
with ethylene, the ethylene content of such copolymers is most
preferably between 45 and 65%, although higher or lower ethylene
contents may be present.
These polymers may be prepared by polymerizing alpha-olefin
monomer, or mixtures of alpha-olefin monomers, or mixtures
comprising ethylene and at least one C.sub.3 to C.sub.28
alpha-olefin monomer, in the presence of a catalyst system
comprising at least one metallocene (e.g., a
cyclopentadienyl-transition metal compound) and an alumoxane
compound. Using this process, a polymer in which 95% or more of the
polymer chains possess terminal ethenylidene-type unsaturation can
be provided. The percentage of polymer chains exhibiting terminal
ethenylidene unsaturation may be determined by FTIR spectroscopic
analysis, titration, or C.sup.13 NMR. Interpolymers of this latter
type may be characterized by the formula
POLY-C(R.sup.1).dbd.CH.sub.2 wherein R.sup.1 is C.sub.1 to C.sub.26
alkyl, preferably C.sub.1 to C.sub.18 alkyl, more preferably
C.sub.1 to C.sub.8 alkyl, and most preferably C.sub.1 to C.sub.2
alkyl, (e.g., methyl or ethyl) and wherein POLY represents the
polymer chain. The chain length of the R.sup.1 alkyl group will
vary depending on the comonomer(s) selected for use in the
polymerization. A minor amount of the polymer chains can contain
terminal ethenyl, i.e., vinyl, unsaturation, i.e.
POLY-CH.dbd.CH.sub.2, and a portion of the polymers can contain
internal monounsaturation, e.g. POLY-CH.dbd.CH(R.sup.1), wherein
R.sup.1 is as defined above. These terminally unsaturated
interpolymers may be prepared by known metallocene chemistry and
may also be prepared as described in U.S. Pat. Nos. 5,498,809;
5,663,130; 5,705,577; 5,814,715; 6,022,929 and 6,030,930.
Another useful class of polymers is polymers prepared by cationic
polymerization of isobutene, styrene, and the like. Common polymers
from this class include polyisobutenes obtained by polymerization
of a C.sub.4 refinery stream having a butene content of about 35 to
about 75% by wt., and an isobutene content of about 30 to about 60%
by wt., in the presence of a Lewis acid catalyst, such as aluminum
trichloride or boron trifluoride. A preferred source of monomer for
making poly-n-butenes is petroleum feedstreams such as Raffinate
II. These feedstocks are disclosed in the art such as in U.S. Pat.
No. 4,952,739. Polyisobutylene is a most preferred backbone of the
present invention because it is readily available by cationic
polymerization from butene streams (e.g., using AlCl.sub.3 or
BF.sub.3 catalysts). Such polyisobutylenes generally contain
residual unsaturation in amounts of about one ethylenic double bond
per polymer chain, positioned along the chain.
As noted above, the polyisobutylene polymers employed are generally
based on a hydrocarbon chain of from about 900 to 2,300. Methods
for making polyisobutylene are known. Polyisobutylene can be
functionalized by halogenation (e.g. chlorination), the thermal
"ene" reaction, or by free radical grafting using a catalyst (e.g.
peroxide), as described below.
Processes for reacting polymeric hydrocarbons with unsaturated
carboxylic acids, anhydrides or esters and the preparation of
derivatives from such compounds are disclosed in U.S. Pat. Nos.
3,087,936; 3,172,892; 3,215,707; 3,231,587; 3,272,746; 3,275,554;
3,381,022; 3,442,808; 3,565,804; 3,912,764; 4,110,349; 4,234,435;
and GB-A-1,440,219. The polymer or hydrocarbon may be
functionalized, for example, with carboxylic acid producing
moieties (preferably acid or anhydride) by reacting the polymer or
hydrocarbon under conditions that result in the addition of
functional moieties or agents, i.e., acid, anhydride, ester
moieties, etc., onto the polymer or hydrocarbon chains primarily at
sites of carbon-to-carbon unsaturation (also referred to as
ethylenic or olefinic unsaturation) using the halogen assisted
functionalization (e.g. chlorination) process or the thermal "ene"
reaction.
When using the free radical grafting process employing a catalyst
(e.g. peroxide), the functionalization is randomly effected along
the polymer chain. Selective functionalization can be accomplished
by halogenating, e.g., chlorinating or brominating the unsaturated
(.alpha.-olefin polymer to about 1 to 8 wt. %, preferably 3 to 7
wt. % chlorine, or bromine, based on the weight of polymer or
hydrocarbon, by passing the chlorine or bromine through the polymer
at a temperature of 60 to 250.degree. C., preferably 110 to
160.degree. C., e.g., 120 to 140.degree. C., for about 0.5 to 10,
preferably 1 to 7 hours. The halogenated polymer or hydrocarbon
(hereinafter backbones) can then be reacted with sufficient
monounsaturated reactant capable of adding functional moieties to
the backbone, e.g., monounsaturated carboxylic reactant, at 100 to
250.degree. C., usually about 180.degree. C. to 235.degree. C., for
about 0.5 to 10, e.g., 3 to 8 hours, such that the product obtained
will contain the desired number of moles of the monounsaturated
carboxylic reactant per mole of the halogenated backbones.
Alternatively, the backbone and the monounsaturated carboxylic
reactant can be mixed and heated while adding chlorine to the hot
material.
The hydrocarbon or polymer backbone can be functionalized, e.g.,
with carboxylic acid producing moieties (preferably acid or
anhydride moieties) selectively at sites of carbon-to-carbon
unsaturation on the polymer or hydrocarbon chains, or randomly
along chains using the three processes mentioned above, or
combinations thereof, in any sequence.
The preferred monounsaturated reactants that are used to
functionalize the backbone comprise mono- and dicarboxylic acid
material, i.e., acid, anhydride, or acid ester material, including
(i) monounsaturated C.sub.4 to C.sub.10 dicarboxylic acid wherein
(a) the carboxyl groups are vicinyl, (i.e., located on adjacent
carbon atoms) and (b) at least one, preferably both, of said
adjacent carbon atoms are part of said mono unsaturation; (ii)
derivatives of (i) such as anhydrides or C.sub.1 to C.sub.5 alcohol
derived mono- or diesters of (i); (iii) monounsaturated C.sub.3 to
C.sub.10 monocarboxylic acid wherein the carbon--carbon double bond
is conjugated with the carboxy group, i.e., of the structure
--C.dbd.C--CO--; and (iv) derivatives of (iii) such as C.sub.1 to
C.sub.5 alcohol derived mono- or diesters of (iii). Mixtures of
monounsaturated carboxylic materials (i)-(iv) also may be used.
Upon reaction with the backbone, the monounsaturation of the
monounsaturated carboxylic reactant becomes saturated. Thus, for
example, maleic anhydride becomes backbone-substituted succinic
anhydride, and acrylic acid becomes backbone-substituted propionic
acid. Exemplary of such monounsaturated carboxylic reactants are
fumaric acid, itaconic acid, maleic acid, maleic anhydride,
chloromaleic acid, chloromaleic anhydride, acrylic acid,
methacrylic acid, crotonic acid, cinnamic acid, and lower alkyl
(e.g., C.sub.1 to C.sub.4 alkyl) acid esters of the foregoing,
e.g., methyl maleate, ethyl fumarate, and methyl fumarate. The
monounsaturated carboxylic reactant, preferably maleic anhydride,
typically will be used in an amount ranging from about 0.01 to
about 20 wt. %, preferably 0.5 to 10 wt. %, based on the weight of
the polymer or hydrocarbon.
While chlorination normally helps increase the reactivity of
starting olefin polymers with monounsaturated functionalizing
reactant, it is not necessary with the polymers or hydrocarbons
contemplated for use in the present invention, particularly those
preferred polymers or hydrocarbons which possess a high terminal
bond content and reactivity. Preferably, therefore, the backbone
and the monounsaturated functionality reactant, e.g., carboxylic
reactant, are contacted at elevated temperature to cause an initial
thermal "ene" reaction to take place. Ene reactions are known.
The hydrocarbon or polymer backbone can be functionalized by random
attachment of functional moieties along the polymer chains by a
variety of methods. For example, the polymer, in solution or in
solid form, may be grafted with the monounsaturated carboxylic
reactant, as described above, in the presence of a free-radical
initiator. When performed in solution, the grafting takes place at
an elevated temperature in the range of about 100 to 260.degree.
C., preferably 120 to 240.degree. C. Preferably, free-radical
initiated grafting is accomplished in a mineral lubricating oil
solution containing, for example, 1 to 50 wt. %, preferably 5 to 30
wt. % polymer based on the initial total oil solution.
The free-radical initiators that may be used are peroxides,
hydroperoxides, and azo compounds, preferably those that have a
boiling point greater than about 100.degree. C. and decompose
thermally within the grafting temperature range to provide
free-radicals. Representative of these free-radical initiators are
azobutyronitrile, 2,5-dimethylhex-3-ene-2,5-bis-tertiary-butyl
peroxide and dicumene peroxide. The initiator, when used, typically
is used in an amount of between 0.005% and 1% by weight based on
the weight of the reaction mixture solution. Typically, the
aforesaid monounsaturated carboxylic reactant material and
free-radical initiator are used in a weight ratio range of from
about 1.0:1 to 30:1, preferably 3:1 to 6:1. The grafting is
preferably carried out in an inert atmosphere, such as under
nitrogen blanketing. The resulting grafted polymer is characterized
by having carboxylic acid (or ester or anhydride) moieties randomly
attached along the polymer chains: it being understood, of course,
that some of the polymer chains remain ungrafted. The free radical
grafting described above can be used for the other polymers and
hydrocarbons of the present invention.
The functionalized oil-soluble polymeric hydrocarbon backbone may
then be further derivatized with a nucleophilic reactant, such as
an amine, amino-alcohol, alcohol, metal compound, or mixture
thereof, to form a corresponding derivative. Useful amine compounds
for derivatizing functionalized polymers comprise at least one
amine and can comprise one or more additional amine or other
reactive or polar groups. These amines may be hydrocarbyl amines or
may be predominantly hydrocarbyl amines in which the hydrocarbyl
group includes other groups, e.g., hydroxy groups, alkoxy groups,
amide groups, nitriles, imidazoline groups, and the like.
Particularly useful amine compounds include mono- and polyamines,
e.g., polyalkene and polyoxyalkylene polyamines of about 2 to 60,
such as 2 to 40 (e.g., 3 to 20) total carbon atoms having about 1
to 12, such as 3 to 12, and preferably 3 to 9 nitrogen atoms per
molecule. Mixtures of amine compounds may advantageously be used,
such as those prepared by reaction of alkylene dihalide with
ammonia. Preferred amines are aliphatic saturated amines,
including, for example, 1,2-diaminoethane; 1,3-diaminopropane;
1,4-diaminobutane; 1,6-diaminohexane; polyethylene amines such as
diethylene triamine; triethylene tetramine; tetraethylene
pentamine; and polypropyleneamines such as 1,2-propylene diamine;
and di-(1,2-propylene)triamine.
Other useful amine compounds include: alicyclic diamines such as
1,4-di(aminomethyl) cyclohexane and heterocyclic nitrogen compounds
such as imidazolines. Another useful class of amines is the
polyamido and related amido-amines as disclosed in U.S. Pat. Nos.
4,857,217; 4,956,107; 4,963,275; and 5,229,022. Also usable is
tris(hydroxymethyl)amino methane (TAM) as described in U.S. Pat.
Nos. 4,102,798; 4,113,639; 4,116,876; and UK 989,409. Dendrimers,
star-like amines, and comb-structured amines may also be used.
Similarly, one may use condensed amines, as described in U.S. Pat.
No. 5,053,152. The functionalized polymer is reacted with the amine
compound using conventional techniques as described, for example,
in U.S. Pat. Nos. 4,234,435 and 5,229,022, as well as in
EP-A-208,560.
The functionalized, oil-soluble polymeric hydrocarbon backbones may
also be derivatized with hydroxy compounds such as monohydric and
polyhydric alcohols, or with aromatic compounds such as phenols and
naphthols. Preferred polyhydric alcohols include alkylene glycols
in which the alkylene radical contains from 2 to 8 carbon atoms.
Other useful polyhydric alcohols include glycerol, mono-oleate of
glycerol, monostearate of glycerol, monomethyl ether of glycerol,
pentaerythritol, dipentaerythritol, and mixtures thereof. An ester
dispersant may also be derived from unsaturated alcohols, such as
allyl alcohol, cinnamyl alcohol, propargyl alcohol,
1-cyclohexane-3-ol, and oleyl alcohol. Still other classes of
alcohols capable of yielding ashless dispersants comprise
ether-alcohols, including oxy-alkylene and oxy-arylene. Such
ether-alcohols are exemplified by ether-alcohols having up to 150
oxy-alkylene radicals in which the alkylene radical contains from 1
to 8 carbon atoms. The ester dispersants may be di-esters of
succinic acids or acid-esters, i.e., partially esterified succinic
acids, as well as partially esterified polyhydric alcohols or
phenols, i.e., esters having free alcohols or phenolic hydroxy
radicals. An ester dispersant may be prepared by any one of several
known methods as described, for example, in U.S. Pat. No.
3,381,022.
Preferred groups of dispersant include polyamine-derivatized poly
.alpha.-olefin, dispersants, particularly ethylene/butene
alpha-olefin and polyisobutylene-based dispersants. Particularly
preferred are ashless dispersants derived from polyisobutylene
substituted with succininc anhydride groups and reacted with
polyethylene amines, e.g., polyethylene diamine, tetraethylene
pentamine; or a polyoxyalkylene polyamine, e.g., polyoxypropylene
diamine, trimethylolaminomethane; a hydroxy compound, e.g.,
pentaerythritol; and combinations thereof. One particularly
preferred dispersant combination is a combination of (A)
polyisobutylene substituted with succinic anhydride groups and
reacted with (B) a hydroxy compound, e.g., pentaerythritol; (C) a
polyoxyalkylene polyamine, e.g., polyoxypropylene diamine, or (D) a
polyalkylene diamine, e.g., polyethylene diamine and tetraethylene
pentamine using about 0.3 to about 2 moles of (B), (C) and/or (D)
per mole of (A). Another preferred dispersant combination comprises
a combination of (A) polyisobutenyl succinic anhydride with (B) a
polyaLkylene polyamine, e.g., tetraethylene pentamine, and (C) a
polyhydric alcohol or polyhydroxy-substituted aliphatic primary
amine, e.g., pentaerythritol or trismethylolaminomethane, as
described in U.S. Pat. No. 3,632,511.
Another class of ashless dispersants comprises Mannich base
condensation products. Generally, these products are prepared by
condensing about one mole of an alkyl-substituted mono- or
polyhydroxy benzene with about 1 to 2.5 moles of carbonyl
compound(s) (e.g., formaldehyde and paraformaldehyde) and about 0.5
to 2 moles of polyalkylene polyamine, as disclosed, for example, in
U.S. Pat. No. 3,442,808. Such Mannich base condensation products
may include a polymer product of a metallocene catalyzed
polymerization as a substituent on the benzene group, or may be
reacted with a compound containing such a polymer substituted on a
succinic anhydride in a manner similar to that described in U.S.
Pat. No. 3,442,808. Examples of functionalized and/or derivatized
olefin polymers synthesized using metallocene catalyst systems are
described in the publications identified supra.
The dispersant can be further post treated by a variety of
conventional post treatments such as boration, as generally taught
in U.S. Pat. Nos. 3,087,936 and 3,254,025. Boration of the
dispersant is readily accomplished by treating an acyl
nitrogen-containing dispersant with a boron compound such as boron
oxide, boron halide boron acids, and esters of boron acids, in an
amount sufficient to provide from about 0.1 to about 20 atomic
proportions of boron for each mole of acylated nitrogen
composition. Useful dispersants contain from about 0.05 to about
2.0 wt. %, e.g., from about 0.05 to about 0.7 wt. % boron. The
boron, which appears in the product as dehydrated boric acid
polymers (primarily (HBO.sub.2).sub.3), is believed to attach to
the dispersant imides and diimides as amine salts, e.g., the
metaborate salt of the diimide. Boration can be carried out by
adding from about 0.5 to 4 wt. %, e.g., from about 1 to about 3 wt.
% (based on the weight of acyl nitrogen compound) of a boron
compound, preferably boric acid, usually as a slurry, to the acyl
nitrogen compound and heating with stirring at from about
135.degree. C. to about 190.degree. C., e.g., 140.degree. C. to
170.degree. C., for from about 1 to about 5 hours, followed by
nitrogen stripping. Alternatively, the boron treatment can be
conducted by adding boric acid to a hot reaction mixture of the
dicarboxylic acid material and amine, while removing water. Other
post reaction processes commonly known in the art can also be
applied.
The third essential component of the composition of the present
invention is substituted aromatic hydrocarbyl oligomer is of the
following formula: ##STR1##
In Formula I, each moiety Ar represents an optionally substituted
aromatic moiety; each L is a linking moiety that is carbon--carbon
single bond or a linking group, n is a number from about 2 to about
1000, and each T is a terminal group. At least 25% of the aromatic
moieties (Ar) are connected to at least 2 linking moieties (L). The
ratio of the total number of aliphatic carbon atoms to aromatic
ring atoms in the substituted aromatic hydrocarbyl oligomer is from
about 0.10:1 to about 40:1.
Aromatic moieties Ar of Formula I can be polynuclear carbocyclic
moieties or mono- or polynuclear heterocyclic moieties. Polynuclear
carbocyclic moieties may comprise two or more fused rings, each
ring having 4 to 10 carbon atoms (e.g., naphthalene). Suitable
carbocyclic polynuclear moieties may also be linked mononuclear
aromatic moieties, such as biphenyl, or may comprise linked, fused
rings (e.g., binaphthyl). Examples of suitable polynuclear
carbocyclic aromatic moieties include naphthalene, anthracene,
phenanthrene, cyclopentenophenanthrene, benzanthracene,
dibenzanthracene, chrysene, pyrene, benzpyrene and coronene and
dimer, trimer and higher polymers thereof. Heterocyclic moieties Ar
include those comprising one or more rings each containing 4 to 10
atoms, including one or more hetero atoms selected from N, O and S.
Examples of suitable monocyclic heterocyclic aromatic moieties
include pyrrole, furan, thiophene, imidazole, oxazole, thiazole,
pyrazole, pyridine, pyrimidine and purine. Suitable polynuclear
heterocyclic moieties Ar include, for example, quinoline,
isoquinoline, carbazole, dipyridyl, cinnoline, phthalazine,
quinazoline, quinoxaline and phenanthroline. Each aromatic moiety
(Ar) may be independently selected such that all moieties (Ar) are
the same or different. The preferred polycyclic carbocyclic
aromatic moiety is naphthalene. Polycyclic heterocycles are
preferred over monocyclic heterocycles. The preferred heterocyclic
aromatic moiety is quinoline.
Each aromatic moiety Ar may independently be unsubstituted or
substituted with 1 to 6 groups selected from H, --OR.sub.1,
--N(R.sub.1).sub.2, F, Cl, Br, I, -(L-(Ar)-T), --S(O).sub.w
R.sub.1, --(CZ).sub.x --(Z).sub.y --R, and --(Z).sub.y --(CZ).sub.x
--R.sub.1, wherein w is 0 to 3, each Z is independently O,
--N(R.sub.1).sub.2 or S, x and y are independently 0 or 1, each
R.sub.1 is independently H or a linear or branched, saturated or
unsaturated hydrocarbyl group having from 1 to about 200 carbon
atoms, optionally mono- or poly-substituted with one or more groups
selected from --OR.sub.2, --N(R.sub.2).sub.2, F, Cl, Br, I,
--S(O).sub.w R.sub.2, --(CZ).sub.x --(Z).sub.y --R.sub.2 and
--(Z).sub.y --(CZ).sub.x --R.sub.2, wherein w, x, y and Z are as
defined above, R.sub.2 is a hydrocarbyl group having 1 to about 200
carbon atoms, and T is a terminal group. Preferably, at least 60%
of the aromatic moieties (Ar) are substituted with at least one of
the aforementioned substituent groups other than H. The oligomer
must be substituted to provide a ratio of the total number of
aliphatic carbons to the total number of aromatic ring atoms that
is from about 0.10:1 to about 40:1, preferably from about 0.10:1 to
about 15:1, most preferably from about 4:1 to about 7:1.
Each linking group (L) may be the same or different, and can be a
carbon to carbon single bond between the carbon atoms of adjacent
moieties Ar, or a linking group. Suitable linking groups include
alkylene linkages, such as --R.sub.3 --, ether linkages, such as
--O--, --O(R.sub.3)--, --O--((R.sub.3)--O).sub.a -- and
--((R.sub.3)--O).sub.a --(R.sub.3)--; acyl linkages, including
--(CO).sub.2 --, --(CO)--(R.sub.3)--,
--(CO)--((R.sub.3)--(CO)).sub.a, --(CO)--((R.sub.3)--(CO)).sub.a
--(R.sub.3)-- and --((R.sub.3)--(CO)).sub.a --(R.sub.3)--; ester
linkages, such as --(CO.sub.2)--, --(CO.sub.2 O--R.sub.3 O--,
(CO.sub.2)--((R.sub.3)--(CO.sub.2)).sub.a --,
(CO.sub.2)--((R.sub.3)--(CO)).sub.a --(R.sub.3)--,
--((R.sub.3)--(CO.sub.2).sub.a --(R.sub.3)--, --(OCO)--(R.sub.3)--,
--(OCO)--((R.sub.3)--(OCO)).sub.a --, and
--(OCO)--((R.sub.3)--(CO.sub.3)).sub.a --; anhydride linkages,
including --(CO.sub.2 CO)--, --(R.sub.3)--(CO.sub.2 CO)-- and
--(R.sub.3)--(CO.sub.2 CO)--(R.sub.3)--; ether-acyl linkages, such
as --O--(R.sub.3)--(CO)--, --(R.sub.3)--O--(R.sub.3)--(CO)--,
--O--(R.sub.3)--(CO)--(R.sub.3)--and
--(R.sub.3)--O--(R.sub.3)--(CO)--(R.sub.3)--; ether-ester linkages
such as --O--(R.sub.3)--(CO.sub.2)--,
--(R.sub.3)--O--(R.sub.3)--(CO.sub.2)--,
--O--(R.sub.3)--(CO.sub.2)--(R.sub.3)--,
--(R.sub.3)--O--(R.sub.3)--(CO.sub.2)--(R.sub.3)--,
--O--(R.sub.3)--(OCO)--, --(R.sub.3)--O--(R.sub.3)--(OCO)--,
--O--(R.sub.3)--(OCO)--(R.sub.3)--, and
--(R.sub.3)--O--(R.sub.3)--(OCO)--(R.sub.3)--; acyl-ester linkages,
including --(CO)--(R.sub.3)--(CO.sub.2)--,
--(R.sub.3)--(CO)--(R.sub.3)--(CO.sub.2)--,
--(CO)--(R.sub.3)--(CO.sub.2)--(R.sub.3)--,
--(R.sub.3)--(CO)--(R.sub.3)--(CO.sub.2)--(R.sub.3)--,
--(CO)--(R.sub.3)--(OCO)--, --(R.sub.3)--(CO)--(R.sub.3)--(OCO)--,
--(CO)--(R.sub.3)--(OCO)--(R.sub.3)--, and
--(R.sub.3)--(CO)--(R.sub.3)--(OCO)--(R.sub.3)--; amino linkages,
such as --N(R.sub.1)--, --N(R.sub.1)--(R.sub.3)--,
--N(R.sub.1)--((R.sub.3)--N(R.sub.1)).sub.a --, and
--((R.sub.3)--N(R.sub.1).sub.a --(R.sub.3)--; amido linkages, for
example, --N(R.sub.1)--(CO)--,
--N(R.sub.1)--(CO)--(R.sub.3)--(CO)--N(R.sub.1)--,
--(CO)--N(R.sub.1)--(R.sub.3)--N(R.sub.1)--(CO)--,
--(CO)--N(R.sub.1)--(R.sub.3)--(CO)--N(R.sub.1)--,
--(R.sub.3)--N(R.sub.1)--(CO)--(R.sub.3)--(CO)--N(R.sub.1)--(R.sub.3)--,
--(R.sub.3)--(CO)--N(R.sub.1)--(R.sub.3)--N(R.sub.1)--(CO)--(R.sub.3)--and
--(R.sub.3)--(CO)--N(R.sub.1)--(R.sub.3)--(CO)--N(R.sub.1)--(R.sub.3)--;
carbamido linkages, such as --N(R.sub.1)--(CO)--N(R.sub.1)--,
--(R.sub.3)--N(R.sub.1)--(CO)--N(R.sub.1)--,
--(R.sub.3)--N(R.sub.1)--(CO)--N(R.sub.1)--(R.sub.3)--; urethane
linkages, including --N(R.sub.1)--(CO.sub.2)--,
--(R.sub.3)--N(R.sub.1)--(CO.sub.2)--,
--N(R.sub.1)--(CO.sub.2)--(R.sub.3)--, and
--(R.sub.3)--N(R.sub.1)--(CO.sub.2)--(R.sub.3)--; and sulfur
linkages, for example --S.sub.c --, --(R.sub.3)--S.sub.c --,
--(R.sub.3)--S.sub.c --(R.sub.3)--, --SO.sub.d --,
--(R.sub.3)--SO.sub.d --, --SO.sub.d --[(R.sub.3)--SO.sub.d ].sub.a
--, --SO.sub.d --[(R.sub.3)--SO.sub.d ].sub.a --(R.sub.3)--and
--[(R.sub.3)--SO.sub.d ].sub.a --(R.sub.2)--; wherein R.sub.1 is as
previously defined, each R.sub.3 is independently a linear or
branched, saturated or unsaturated hydrocarbyl group having from 1
to about 100 carbon atoms, more preferably from 1 to about 30
carbon atoms, and most preferably from 1 to about 10 carbon atoms,
optionally mono- or polysubstituted with OR.sub.1,
N(R.sub.1).sub.2, F, Cl, Br, I, S(O).sub.w R.sub.1, (CZ).sub.x
--(Z).sub.y --R.sub.1, (Z).sub.y --(CZ).sub.x --R.sub.1, wherein w
and Z are as previously defined; a is from about 1 to about 40, b
is either 1 or 2, c is from about 1 to about 8, and d is from about
1 to about 3.
Preferred linking groups are alkylene linkages such as --CH.sub.3
CHC(CH.sub.3).sub.2 --, or --C(CH.sub.3).sub.2 --; diacyl linkages
such as --COCO-- or --CO(CH.sub.2).sub.4 CO--; and sulfur linkages,
such as --S.sub.1 -- or --S.sub.2 --. When the aromatic moiety (Ar)
is substituted with an OH substituent, the preferred linking group
is --CH.sub.2 --. The number of aliphatic atoms and aromatic carbon
atoms in linking moiety (L) are not included when calculating the
ratio of aliphatic to of aromatic carbons for the oligomer.
Each terminal group (T) is independently selected from H, OR.sub.1,
N(R.sub.1)2, F, Cl, Br, I, S(O).sub.w R.sub.1, (CZ).sub.x
--(Z).sub.y --R.sub.1 or (Z).sub.y --(CZ).sub.x --R.sub.1, wherein
R.sub.1, w, x, y and Z are as previously defined.
Methods for forming compounds of Formula I should be apparent to
those of ordinary skill in the art. The, aromatic moiety Ar may be
substituted by, for example, alkylated, prior to or subsequent to
linkage. To form the oligomer of Formula I, individual aromatic
moieties Ar may be reacted with a polyhalogenated (preferably
dihalogenated) hydrocarbon (e.g., 1,4-dichlorobutane,
2,2-dichloropropane, etc.), or a di- or poly-olefin (e.g.,
butadiene, isoprene, 1,4-hexadiene, 1,5-hexadiene, etc.) to yield a
compound of Formula I having an alkylene linking groups. Reaction
of aromatic moieties Ar and a ketone or aldehyde (e.g.,
formaldehyde, acetone, benzophenone, acetophenone, etc.) provides
an alkylene linked compound. An acyl-linked compound can be formed
by reacting aromatic moieties Ar with a diacid or anhydride (e.g.,
oxalic acid, malonic acid, succinic acid, glutaric acid, adipic
acid, succinic anhydride, etc.). Sulfide, polysulfide, sulfinyl and
sulfonyl linkages may be provided by reacting the aromatic moieties
Ar with a suitable difunctional sulfurizing agent (e.g., sulfur
monochloride, sulfur dichloride, thionyl chloride (SOCl.sub.2),
sulfuryl chloride (SO.sub.2 Cl.sub.2), etc.). To provide a compound
of Formula I with an alkylene ether linkage, hydroxy-substituted
aromatic moieties Ar can be reacted with a dihalide (e.g.,
1,2-dichloroethane, 1,3-diiodopropane, 1,6-dichlorohexane, etc.).
Oligomers of Formula I, wherein L is a direct carbon to carbon
link, may be formed via oxidative coupling polymerization using a
mixture of aluminum chloride and cuprous chloride, as described,
for example, by P. Kovacic, et al., J. Polymer Science: Polymer
Chem. Ed., 21, 457 (1983). Alternatively, such oligomers may be
formed by reacting aromatic moieties Ar and an alkali metal as
described, for example, in "Catalytic Benzene Coupling on
Caesium/Nanoporous Carbon Catalysts", M. G. Stevens, K. M. Sellers,
S. Subramoney and H. C. Foley, Chemical Communications, 2679-2680
(1988). The degree of polymerization of the substituted aromatic
oligomers of Formula I range from 2 to about 1,000 (corresponding
to a value of n of from 1 to about 998), preferably from about 5 to
about 200, most preferably from about 10 to about 50.
Novel compounds of Formula I include those wherein each Ar
independently represents an aromatic moiety optionally substituted
by 1 to 4 substituents selected from H, --OR.sub.4,
--N(R.sub.4).sub.2, F, Cl, Br, I, -(L-(Ar)-T), --S(O).sub.w
R.sub.4, -(CZ).sub.x -(Z).sub.y --R.sub.4 and -(Z).sub.y
-(CZ).sub.x R.sub.4, wherein w is 0 to 3, each Z is independently
O, --N(R.sub.4).sub.2 or S, x and y are independently 0 or 1 and
each R.sub.4 is independently H, methyl, ethyl, propyl or a
branched hydrocarbyl group having 3 to 200 carbon atoms, optionally
mono- or poly-substituted with one or more groups selected from
--OR.sub.4, --N(R.sub.4).sub.2, F, Cl, Br, I, --S(O).sub.w R.sub.4,
-(CZ).sub.x -(Z).sub.y R.sub.4 and -(Z).sub.y -(CZ).sub.x
--R.sub.4, wherein w, x, y, T, R.sub.4 and Z are as defined
above.
For adequate control of soot induced viscosity increase, a high
molecular weight dispersant is conventionally added in an amount of
5 to 12 mass %, based on the total mass of the finished lubricant.
These dispersants typically have a nitrogen content of about 1 wt.
%. Thus, a typical lubricant composition will contain from about
0.10 wt % to about 0.12 wt. % of nitrogen from dispersant. In
contrast, a finished lubricant containing from about 0.005 to 10
wt. % (preferably about 0.1 to about 5 wt. %, more preferably about
0.5 to about 2 wt. %) of an oligomer of Formula I provides
comparable soot dispersant characteristics with only about 2.5 to
about 9.5 wt. %, preferably about 2 to 3 wt. % of dispersant, which
adds to the lubricant composition only about 0.025 to about 0.095
wt. %, preferably from about 0.02 to about 0.03 wt. % of nitrogen.
In general, each 0.5 wt. % increase in the amount of oligomer of
Formula I could allow up to a 2.5 wt. % reduction in the amount of
needed dispersant. A preferred lubricating oil composition of the
invention may contain an amount of high molecular weight dispersant
in an amount providing from about 0.008 to about 0.32 wt. % of
nitrogen, and an oligomer of Formula I in an amount of from about
0.005 to about 10 wt. %, based on the total weight of lubricating
oil composition.
OTHER ADDITIVE COMPONENTS
Additional additives may be incorporated in the compositions of the
invention to enable them to meet particular requirements. Examples
of additives which may be included in the lubricating oil
compositions are detergents, metal rust inhibitors, viscosity index
improvers, corrosion inhibitors, oxidation inhibitors, friction
modifiers, other dispersants, anti-foaming agents, anti-wear agents
and pour point depressants. Some are discussed in further detail
below.
Metal-containing or ash-forming detergents function both as
detergents to reduce or remove deposits and as acid neutralizers or
rust inhibitors, thereby reducing wear and corrosion and extending
engine life. Detergents generally comprise a polar head with a long
hydrophobic tail, with the polar head comprising a metal salt of an
acidic organic compound. The salts may contain a substantially
stoichiometric amount of the metal in which case they are usually
described as normal or neutral salts, and would typically have a
total base number or TBN (as can be measured by ASTM D2896) of from
0 to 80. A large amount of a metal base may be incorporated by
reacting excess metal compound (e.g., an oxide or hydroxide) with
an acidic gas (e.g., carbon dioxide). The resulting overbased
detergent comprises neutralized detergent as the outer layer of a
metal base (e.g. carbonate) micelle. Such overbased detergents may
have a TBN of 150 or greater, and typically will have a TBN of from
250 to 450 or more.
Detergents that may be used include oil-soluble neutral and
overbased sulfonates, phenates, sulfurized phenates,
thiophosphonates, salicylates, and naphthenates and other
oil-soluble carboxylates of a metal, particularly the alkali or
alkaline earth metals, e.g., sodium, potassium, lithium, calcium,
and magnesium. The most commonly used metals are calcium and
magnesium, which may both be present in detergents used in a
lubricant, and mixtures of calcium and/or magnesium with sodium.
Particularly convenient metal detergents are neutral and overbased
calcium sulfonates having TBN of from 20 to 450 TBN, and neutral
and overbased calcium phenates and sulfurized phenates having TBN
of from 50 to 450. Combinations of detergents, whether overbased or
neutral or both, may be used.
Sulfonates may be prepared from sulfonic acids which are typically
obtained by the sulfonation of alkyl substituted aromatic
hydrocarbons such as those obtained from the fractionation of
petroleum or by the alkylation of aromatic hydrocarbons. Examples
included those obtained by alkylating benzene, toluene, xylene,
naphthalene, diphenyl or their halogen derivatives such as
chlorobenzene, chlorotoluene and chloronaphthalene. The alkylation
may be carried out in the presence of a catalyst with alkylating
agents having from about 3 to more than 70 carbon atoms. The
alkaryl sulfonates usually contain from about 9 to about 80 or more
carbon atoms, preferably from about 16 to about 60 carbon atoms per
alkyl substituted aromatic moiety.
The oil soluble sulfonates or alkaryl sulfonic acids may be
neutralized with oxides, hydroxides, alkoxides, carbonates,
carboxylate, sulfides, hydrosulfides, nitrates, borates and ethers
of the metal. The amount of metal compound is chosen having regard
to the desired TBN of the final product but typically ranges from
about 100 to 220 wt. % (preferably at least 125 wt. %) of that
stoichiometrically required.
Metal salts of phenols and sulfurized phenols are prepared by
reaction with an appropriate metal compound such as an oxide or
hydroxide and neutral or overbased products may be obtained by
methods well known in the art. Sulfurized phenols may be prepared
by reacting a phenol with sulfur or a sulfur containing compound
such as hydrogen sulfide, sulfur monohalide or sulfur dihalide, to
form products which are generally mixtures of compounds in which 2
or more phenols are bridged by sulfur containing bridges.
Dihydrocarbyl dithiophosphate metal salts are frequently used as
antiwear and antioxidant agents. The metal may be an alkali or
alkaline earth metal, or aluminum, lead, tin, molybdenum,
manganese, nickel or copper. The zinc salts are most commonly used
in lubricating oil in amounts of 0.1 to 10, preferably 0.2 to 2 wt.
%, based upon the total weight of the lubricating oil composition.
They may be prepared in accordance with known techniques by first
formiing a dihydrocarbyl dithiophosphoric acid (DDPA), usually by
reaction of one or more alcohol or a phenol with P.sub.2 S.sub.5
and then neutralizing the formed DDPA with a zinc compound. For
example, a dithiophosphoric acid may be made by reacting mixtures
of primary and secondary alcohols. Alternatively, multiple
dithiophosphoric acids can be prepared where the hydrocarbyl groups
on one are entirely secondary in character and the hydrocarbyl
groups on the others are entirely primary in character. To make the
zinc salt, any basic or neutral zinc compound could be used but the
oxides, hydroxides and carbonates are most generally employed.
Commercial additives frequently contain an excess of zinc due to
the use of an excess of the basic zinc compound in the
neutralization reaction.
The preferred zinc dihydrocarbyl dithiophosphates are oil soluble
salts of dihydrocarbyl dithiophosphoric acids and may be
represented by the following formula: ##STR2##
wherein R and R' may be the same or different hydrocarbyl radicals
containing from 1 to 18, preferably 2 to 12, carbon atoms and
including radicals such as alkyl, alkenyl, aryl, arylalkyl, alkaryl
and cycloaliphatic radicals. Particularly preferred as R and
R.sup.1 groups are alkyl groups of 2 to 8 carbon atoms. Thus, the
radicals may, for example, be ethyl, n-propyl, i-propyl, n-butyl,
i-butyl, sec-butyl, amyl, n-hexyl, i-hexyl, n-octyl, decyl,
dodecyl, octadecyl, 2-ethylhexyl, phenyl, butylphenyl, cyclohexyl,
methylcyclopentyl, propenyl, butenyl. In order to obtain oil
solubility, the total number of carbon atoms (i.e. R and R') in the
dithiophosphoric acid will generally be about 5 or greater. The
zinc dihydrocarbyl dithiophosphate can therefore comprise zinc
dialkyl dithiophosphates. The present invention may be particularly
useful when used with lubricant compositions containing phosphorus
levels of from about 0.02 to about 0.12 wt. %, preferably from
about 0.03 to about 0.10 wt. %, most preferably from about 0.05 to
about 0.08 wt. %, based on the total weight of the composition.
Oxidation inhibitors or antioxidants reduce the tendency of mineral
oils to deteriorate in service. Oxidative deterioration can be
evidenced by sludge in the lubricant, varnish-like deposits on the
metal surfaces, and by viscosity growth. Such oxidation inhibitors
include hindered phenols, alkaline earth metal salts of
alkylphenolthioesters having preferably C.sub.5 to C.sub.12 alkyl
side chains, calcium nonylphenol sulfide, oil soluble phenates and
sulfurized phenates, phosphosulfurized or sulfurized hydrocarbons,
phosphorous esters, metal thiocarbamates, oil soluble copper
compounds as described in U.S. Pat. No. 4,867,890, and
molybdenum-containing compounds.
Aromatic amines having at least two aromatic groups attached
directly to the nitrogen constitute another class of compounds that
is frequently used for antioxidancy. While these materials may be
used in small amounts, preferred embodiments of the present
invention are free of these compounds. They are preferably used in
only small amounts, i.e., up to 0.4 wt. %, or more preferably
avoided altogether other than such amount as may result as an
impurity from another component of the composition.
Typical oil soluble aromatic amines having at least two aromatic
groups attached directly to one amine nitrogen contain from 6 to 16
carbon atoms. The amines may contain more than two aromatic groups.
Compounds having a total of at least three aromatic groups in which
two aromatic groups are linked by a covalent bond or by an atom or
group (e.g., an oxygen or sulfur atom, or a --CO--, --SO.sub.2 --
or alkylene group) and two are directly attached to one amine
nitrogen also considered aromatic amines having at least two
aromatic groups attached directly to the nitrogen. The aromatic
rings are typically substituted by one or more substituents
selected from alkyl, cycloalkyl, alkoxy, aryloxy, acyl, acylamino,
hydroxy, and nitro groups. The amount of any such oil soluble
aromatic amines having at least two aromatic groups attached
directly to one amine nitrogen should preferably not exceed 0.4 wt.
% active ingredient.
Representative examples of suitable viscosity modifiers are
polyisobutylene, copolymers of ethylene and propylene,
polymethacrylates, methacrylate copolymers, copolymers of an
unsaturated dicarboxylic acid and a vinyl compound, interpolymers
of styrene and acrylic esters, and partially hydrogenated
copolymers of styrene/isoprene, styrene/butadiene, and
isoprene/butadiene, as well as the partially hydrogenated
homopolymers of butadiene and isoprene.
Friction modifiers and fuel economy agents that are compatible with
the other ingredients of the final oil may also be included.
Examples of such materials include glyceryl monoesters of higher
fatty acids, for example, glyceryl mono-oleate; esters of long
chain polycarboxylic acids with diols, for example, the butane diol
ester of a dimerized unsaturated fatty acid; oxazoline compounds;
and alkoxylated alkyl-substituted mono-amines, diamines and alkyl
ether amines, for example, ethoxylated tallow amine and ethoxylated
tallow ether amine.
A viscosity index improver dispersant functions both as a viscosity
index improver and as a dispersant. Examples of viscosity index
improver dispersants include reaction products of amines, for
example polyamines, with a hydrocarbyl-substituted mono -or
dicarboxylic acid in which the hydrocarbyl substituent comprises a
chain of sufficient length to impart viscosity index improving
properties to the compounds. In general, the viscosity index
improver dispersant may be, for example, a polymer of a C.sub.4 to
C.sub.24 unsaturated ester of vinyl alcohol or a C.sub.3 to
C.sub.10 unsaturated mono-carboxylic acid or a C.sub.4 to C.sub.10
di-carboxylic acid with an unsaturated nitrogen-containing monomer
having 4 to 20 carbon atoms; a polymer of a C.sub.2 to C.sub.20
olefin with an unsaturated C.sub.3 to C.sub.10 mono- or
di-carboxylic acid neutralised with an amine, hydroxyamine or an
alcohol; or a polymer of ethylene with a C.sub.3 to C.sub.20 olefin
further reacted either by grafting a C.sub.4 to C.sub.20
unsaturated nitrogen-containing monomer thereon or by grafting an
unsaturated acid onto the polymer backbone and then reacting
carboxylic acid groups of the grafted acid with an amine, hydroxy
amine or alcohol.
Pour point depressants, otherwise known as lube oil flow improvers
(LOFI), lower the minimum temperature at which the fluid will flow
or can be poured. Such additives are well known. Typical of those
additives that improve the low temperature fluidity of the fluid
are C.sub.8 to C.sub.18 dialkyl fumarate/vinyl acetate copolymers,
and polymethacrylates. Foam control can be provided by an
antifoamant of the polysiloxane type, for example, silicone oil or
polydimethyl siloxane.
Some of the above-mentioned additives can provide a multiplicity of
effects; thus for example, a single additive may act as a
dispersant-oxidation inhibitor. This approach is well known and
need not be further elaborated herein.
In the present invention it may be necessary to include an additive
which maintains the stability of the viscosity of the blend. Thus,
although polar group-containing additives achieve a suitably low
viscosity in the pre-blending stage it has been observed that some
compositions increase in viscosity when stored for prolonged
periods. Additives which are effective in controlling this
viscosity increase include the long chain hydrocarbons
functionalized by reaction with mono- or dicarboxylic acids or
anhydrides which are used in the preparation of the ashless
dispersants as hereinbefore disclosed.
When lubricating compositions contain one or more of the
above-mentioned additives, each additive is typically blended into
the base oil in an amount that enables the additive to provide its
desired function.
It may be desirable, although not essential, to prepare one or more
additive concentrates comprising additives (concentrates sometimes
being referred to as additive packages) whereby several additives
can be added simultaneously to the oil to form the lubricating oil
composition.
The final lubricant composition may employ from 5 to 25 mass %,
preferably 5 to 18 mass %, typically 10 to 15 mass % of the
concentrate, the remainder being oil of lubricating viscosity.
When lubricating compositions contain one or more of the
above-mentioned additives, each additive is typically blended into
the base oil in an amount that enables the additive to provide its
desired function. Representative effect amounts of such additives,
when used in crankcase lubricants, are listed below. All the values
listed are stated as mass percent active ingredient.
MASS % MASS % ADDITIVE (Broad) (Preferred) Metal Detergents 0.1-15
0.2-9 Corrosion Inhibitor 0-5 0-1.5 Metal Dihydrocarbyl
Dithiophosphate 0.1-6 0.1-4 Antioxidant 0-5 0.01-2 Pour Point
Depressant 0.01-5 0.01-1.5 Antifoaming Agent 0-5 0.001-0.15
Supplemental Antiwear Agents 0-1.0 0-0.5 Friction Modifier 0-5
0-1.5 Viscosity Modifier 0.01-10 0.25-3 Basestock Balance
Balance
All weight percents expressed herein (unless otherwise indicated)
are based on active ingredient (A.I.) content of the additive,
and/or upon the total weight of any additive-package, or
formulation which will be the sum of the A.I. weight of each
additive plus the weight of total oil or diluent.
This invention will be further understood by reference to the
following examples, wherein all parts are parts by weight, unless
otherwise noted.
EXAMPLES
Synthesis Example A
Alkylation of Naphthalene
About 0.4 mole (51.2 g) naphthalene, 1.0 mole (252 g) of
1-octadecene, and 200 ml of heptane are charged into a reaction
flask. About 2 g of boron trifluoride were bubbled into the liquid
and stirred under nitrogen. The reaction flask was then heated to
40.degree. C. to dissolve the naphthalene. The temperature was
increased to 100.degree. C. and the reaction mixture was soaked at
this temperature for one hour. The reaction mixture was then
quenched with an ammonium hydroxide solution. The organic layer was
separated, dried and stripped under vacuum at 200.degree. C.
C.sup.13 NMR analysis showed a mixture of mono- and di-alkylated
naphthalene. The reaction scheme is shown, below: ##STR3##
Synthesis Example B
Linking alkylated Naphthalene
Dodecyl naphthalene (29.6 g, 0.10 mol) in 200 ml of methylene
chloride was charged into a 500 ml round bottom flask. The dodecyl
naphthalene was derived from naphthalene and dodecene in a manner
analogous to that described in Synthesis Example A. The solution
was cooled to 5.degree. C. with stirring under a blanket of dry
nitrogen. Anhydrous aluminum chloride (14.7 g) was added to the
solution. A solution of adipoyl chloride (15.2 g, 0.08 mol) inlSO
ml methylene chloride, was added dropwise over 30 min and the
mixture were stirred for 1 hr at 5.degree. C. The mixture was then
allowed to slowly warm over 2 hr to room temperature. The mixture
was subsequently poured onto 200 g of ice. The organic layer was
separated in a separatory funnel, washed successively with water,
5% aqueous sodium bicarbonate and stripped on a rotary evaporator
to yield 22.5 g of product (62%). An infrared spectrum of the
product showed a strong absorption at 1676 cm.sup.-1,
characteristic of a conjugated aromatic ketone. Gel permeation
chromatography, coupled with C.sup.13 --NMR analysis indicated that
product was a trimer. The reaction scheme is shown, below:
##STR4##
Synthesis Example C
Alkylation of Quinoline
About 1.0 mole (129 g) quinoline and 1.0 mole (252 g) of octadecene
are charged into a reaction flask. About 20 g of F-20X, an acidic
clay obtained from Engelhard Chemicals, are added to the reaction
flask and the reaction mixture is slowly heated to 180.degree. C.
while stirring under nitrogen. The reaction mixture is then soaked
at this temperature for four hours. The reaction mixture is diluted
in heptane and filtered to separate the solid catalyst. The heptane
solution is then stripped under nitrogen at 100.degree. C. until
constant weight. The product obtained is a mixture of
mono-/di-substituted as indicated by GC analysis. If one desires
the di-substituted product to be the major component, an excess
olefin can be used. The reaction scheme is shown, below:
##STR5##
Synthesis Example D
Linking Alkylated Quinoline
About 38.1 g (0.1 mole) of octadecyl quinoline in 200 ml of
methylene chloride was charged into a 500 ml round bottom flask.
The solution was cooled to 5.degree. C. with stirring under a
blanket of dry nitrogen. Anhydrous aluminum chloride (14.7 g) was
added to the solution. A solution of adipoyl chloride (15.2 g, 0.08
mol) in 150 ml methylene chloride, was added dropwise over 30 min
and the mixture were stirred for 1 hr at 5.degree. C. The mixture
was then allowed to slowly warm over 2 hr to room temperature. The
mixture was subsequently poured onto 200 g of ice. The organic
layer was separated in a separatory funnel, washed successively
with water and 5% aqueous sodium bicarbonate and stripped on a
rotary evaporator to yield 22.5 g of product (62%). An infrared
spectrum of the product showed a strong absorption at 1676
cm.sup.-1, characteristic of a conjugated aromatic ketone. Gel
permeation chromatography indicated that product contained on
average three alkyl quinoline units per chain. The reaction scheme
is shown, below: ##STR6##
Example 1
The ability of a composition to control soot-induced viscosity
increase, and thus, the ability of a composition to maintain soot
in suspension, can be measured using bench tests, such as a Haake
Carbon Black Test. The Haake Carbon Black Test involves the
blending of a base oil and additive components to provide a
formulated oil. Carbon black powder is then added to the formulated
oil and the sample is blended overnight. The viscosity of the
carbon black dispersion is then measured in the Haake rheometer
over a range of shear rates from 0.1 sec.sup.-1 to 30 sec.sup.-1.
Typically, the viscosity at shear rates of 0.26 sec.sup.-1 and 0.45
sec.sup.-1 are used for comparison.
The performance of the linked aromatic oligomer of the present
invention as a dispersant booster was tested in the Haake rheometer
using a formulated oil containing detergent, antioxidant, antiwear
agent and 4 wt. % (2% AI) of a high molecular weight PIBSA-PAM
dispersant. The high molecular weight PIBSA-PAM dispersant was
derived from PIBSA having a molecular weight of about 2200, and a
succination ratio of about 1.1. The formulated oils were tested at
a 4.76% carbon black level. The results with formulated oils
containing 1 wt. % and 2 wt. % of the linked aromatic oligomer
additive are presented in FIGS. 1 and 2, respectively. The linked
aromatic oligomer additive was the reaction product of the Friedel
Craft reaction of the C.sub.12 alkylated naphthalene with adipoyl
chloride as described in Synthesis Example B. For comparison,
formulations containing an analogous, unlinked alkylated
naphthalene at 1 wt. % and 2 wt. %., and a formulation containing 4
wt. % (2% AI) of the high molecular weight dispersant, were also
tested. The results, as shown in FIG. 1 and FIG. 2, clearly
demonstrate the superior control of soot induced viscosity increase
(a reduction in viscosity of at least 70%) in formulations
containing 4 wt. % (2% AI) of a high molecular weight dispersant
and a minor amount (1 or 2 wt. %) of the linked aromatic oligomer
of the present invention, when compared to (A) formulations
containing 4 wt. % (2% AI) of a high molecular weight dispersant
and 1 or 2 wt. % of alkylated naphthalene and (B) formulations
containing only 4 wt. % (2% AI) of a high molecular weight
dispersant.
The disclosures of all patents, articles and other materials
described herein are hereby incorporated, in their entirety, into
this specification by reference. The principles, preferred
embodiments and modes of operation of the present invention have
been described in the foregoing specification. What applicants
submit is their invention, however, is not to be construed as
limited to the particular embodiments disclosed, since the
disclosed embodiments are regarded as illustrative rather than
limiting. Changes may be made by those skilled in the art without
departing from the spirit of the invention.
* * * * *